Steering wheel assemblies are a common component of vehicles and typically include a metal armature, or core, covered by a resin and an outer covering. The resin is typically a polyurethane resin that is foamed over the entire armature including the rim, spokes, and hub portions. The outer covering represents the visible portion of the steering wheel assembly and may include one or more layers and may be made of various materials. Even more, the one or more outer covering layers may be formed in sections for positioning over the foamed resin layer.
Application of the resin layer in this manner in the manufacturing process typically involves setting the metal armature in a tool and foaming the resin layer over the armature. In this manner, the resin encapsulates the armature and the resulting assembly includes a complete polyurethane resin layer formed over the rim, spokes, and back-cover of the armature. While this method of manufacturing the armature is sufficient in many regards, the method is not optimized.
Due to the size of the steering wheel, the foaming process can have lengthy cycle times and requires extensive trimming of flash, gates, and/or vents. In addition, the molding parameters must be continuously adjusted in order to reduce the amount of scrap material. Even more, the foaming method results in the loss of grain definition in complex areas having low draft angles, and the incorporation of additional slides to address die-lock conditions. Equally important, the completed the steering wheel assembly does not lend itself to serviceability in the field due to its unitary construction.
Accordingly, a need exists for a steering wheel assembly that is serviceable in the field, i.e., the steering wheel assembly is able to be taken apart to repair and/or replace component parts thereof. Even more, the steering wheel assembly should be designed to reduce material scrap rates in the manufacturing process. Such a steering wheel assembly would necessarily include separating the resin and outer layers of the steering wheel rim and spokes into individual sections thus allowing for faster manufacturing, lower scrap rates, and ease of service and partial replacement.